Strain gauge distribution for resistive strain gauge pressure sensor

Abstract

A resistive strain gauge pressure sensor including upper and lower housings coacting to define a pressure chamber within the housing A board member is clamped between the housings and defines a diaphragm portion which extends across the pressure chamber to divide the pressure chamber into upper and lower chamber portions. All of the circuitry of the sensor is screen printed onto the lower planar face of the board member including the various resistor elements of the strain gauge assembly, the various elements of the conditioning circuit receiving the output of the strain gauge assembly, and the various further leads required to connect the circuitry elements to the terminals of the sensor. The sensor terminals are provided by a plurality of connector pins extending downwardly through the board member for connection at their respective lower ends to the circuitry provided on the lower face of the board member. The resistors of the strain gauge circuitry include a first pair of resistors positioned in a central region of the diaphragm on the transverse midline of the diaphragm in straddling relation to the longitudinal midline of the diaphragm and a second pair of resistors positioned on a peripheral portion of the diaphragm in straddling relation to the longitudinal midline of the diaphragm and in respective longitudinal alignment with the first pair of resistors. The bridge circuitry further includes a thermistor positioned on a region of the diaphragm that experiences substantially no strain in response to the deflection of the diaphragm.